Grain-oriented electrical steel sheet and method for manufacturing same

Abstract

Disclosed are a grain-oriented electrical steel sheet and a method of manufacturing the same. The method for manufacturing a grain-orientated electrical steel sheet according to an exemplary embodiment of the present invention includes: providing an electrical steel sheet before forming primary recrystallization or after forming the primary recrystallization; and forming a groove in a surface of the electrical steel sheet by radiating laser and simultaneously spraying gas onto the electrical steel sheet, in which energy density E d and a laser scanning speed V s of the radiated laser satisfy the following conditions, 1.0 J/mm 2 ≤E d ≤5.0 J/mm 2 , 0.0518 mm/μsec≤ V s ≤0.2 mm/μsec.

The invention claimed is: 
     
       1. A grain-oriented electrical steel sheet, which has a surface which is formed with grooves for a magnetic domain refinement treatment,
 wherein a scattering alloy layer in the groove is eroded in a Goss texture during a recrystallization annealing process, 
 wherein when a thickness of the scattering alloy layer on a bottom surface of the groove is defined as T B , and a thickness of the scattering alloy layer at a point that is one-half the distance between any one end of the groove and the bottom surface of the groove is defined as T L , T B /T L  is 0.2 to 0.8, and 
 wherein the groove is formed at an angle greater than 0° and equal to or smaller than 5° with respect to the width direction of the electrical steel sheet. 
 
     
     
       2. The grain-oriented electrical steel sheet of  claim 1 , wherein:
 a thickness of the scattering alloy layer is 4% to 12% of a depth of the groove. 
 
     
     
       3. The grain-oriented electrical steel sheet of  claim 2 , wherein:
 the depth of the groove is 4% to 11% of a thickness of the electrical steel sheet. 
 
     
     
       4. The grain-oriented electrical steel sheet of  claim 3 , wherein:
 the groove is formed diagonally with respect to a width direction of the electrical steel sheet. 
 
     
     
       5. The grain-oriented electrical steel sheet of  claim 1 , wherein:
 three to six grooves are intermittently formed in the width direction of the electrical steel sheet. 
 
     
     
       6. A method of manufacturing a grain-oriented electrical steel sheet, the method comprising:
 providing an electrical steel sheet before forming primary recrystallization or after forming the primary recrystallization; and 
 forming a groove in a surface of the electrical steel sheet by radiating laser and simultaneously spraying gas onto the electrical steel sheet, 
 wherein energy density E d  and a laser scanning speed V s  of the radiated laser satisfy the following conditions,
   1.0 J/mm 2   ≤E   d ≤5.0 J/mm 2 ,
 
   0.0518 mm/μsec≤ V   s ≤0.2 mm/μsec,
 
 
 wherein a scattering alloy layer in the groove is eroded in a Goss texture during a recrystallization annealing process, and 
 wherein when a thickness of the scattering alloy layer on a bottom surface of the groove is defined as T B , and a thickness of the scattering alloy layer at a point that is one-half the distance between any one end of the groove and the bottom surface of the groove is defined as T L , T B /T L  is 0.2 to 0.8, and 
 wherein the groove is formed at an angel greater than 0° and equal to or smaller than 5° with respect to the width direction of the electrical steel sheet. 
 
     
     
       7. The method of  claim 6 , wherein:
 pressure of the sprayed gas is 0.2 kg/cm 2  to 5.0 kg/cm 2 . 
 
     
     
       8. The method of  claim 7 , wherein:
 an angle formed between the spray direction of the gas and the laser radiation direction is 0° to 50° (here, a state in which the angle formed between the spray direction of the gas and the laser radiation direction is 0° means that the spray direction of the gas and the laser radiation direction are parallel to each other). 
 
     
     
       9. The method of  claim 8 , wherein:
 in the radiating of the laser, a laser beam is radiated on the surface of the electrical steel sheet at an angle greater than 0° and equal to or smaller than 5° with respect to a width direction of the electrical steel sheet. 
 
     
     
       10. The method of  claim 9 , wherein:
 in the radiating of the laser, a movement speed V L  of the electrical steel sheet is at least 0.9 m/s. 
 
     
     
       11. The method of  claim 10 , wherein:
 in the radiating of the laser, 
 when a beam length in the width direction of the electrical steel sheet is d t , and a beam length in a rolling direction of the electrical steel sheet is L, a light collecting shape of the laser satisfies the following condition,
   0.20≤ L/d   t ≤1.0.
 
 
 
     
     
       12. The method of  claim 11 , wherein:
 d t  is 50 μm or smaller. 
 
     
     
       13. The method of  claim 12 , wherein:
 in the radiating of the laser, 
 a scattering alloy layer in which a melted portion of the electrical steel sheet by the radiation of the laser scatters and is resolidified is generated. 
 
     
     
       14. The method of  claim 13 , wherein:
 a thickness of the scattering alloy layer is 4% to 12% of a depth of the groove. 
 
     
     
       15. The method of  claim 14 , wherein:
 in the radiating of the laser, 
 the laser is radiated diagonally with respect to a width direction of the electrical steel sheet. 
 
     
     
       16. The method of  claim 15 , wherein:
 in the radiating of the laser, 
 the laser is radiated at an angle greater than 0° and equal to or smaller than 5° with respect to the width direction of the electrical steel sheet. 
 
     
     
       17. The method of  claim 16 , wherein:
 in the radiating of the laser, 
 three to six grooves are intermittently formed in the width direction of the electrical steel sheet.